The present invention relates to a television antenna system employing a single antenna for reception of both UHF and VHF television signals.
Television sets manufactured for use in the United States are required by FCC regulations to be capable of receiving all UHF and VHF commercial and public television channels. To accomplish this, television receivers uniformly employ UHF and VHF converters or tuners and normally utilize two antenna systems, one for UHF signal reception, and the other for VHF signal reception. In weak signal areas frequently individual outdoor UHF and VHF antennas are coupled to the respective UHF and VHF tuners. It is accordingly highly desirable in the design of television receivers to provide external access to the UHF and VHF tuners.
In stronger signal areas, indoor ring or closed loop antennas are typically coupled to the UHF tuner and indoor dipole or "rabbit ear" antennas are typically coupled to the VHF tuner. Coupling in both cases is removably effected through a terminal block which allows external access to the UHF and VHF tuners for connection to outdoor antennas.
Use of separate antennas for UHF and VHF reception involves an obvious duplication of material, space and cost which might be eliminated by a single antenna system. However, while single antenna systems reduce the number of antennas from two to one, in the past, single antenna systems have required an additional crossover network or switching device not employed in a dual antenna system to allow the UHF and VHF tuners to be selectively coupled to the single antenna. The need for additional components in a single antenna system ranges from an employment of a simple inductor as disclosed in the R. D. Ives U.S. Pat. No. 3,530,473, issued Sept. 22, 1970, to utilization of a high pass, low pass filter as disclosed in the E. K. Von Fange U.S. Pat. No. 3,522,608, issued Aug. 4, 1970 and assigned to the assignee of the present invention. It is, accordingly, an object of the present invention to provide a single antenna system for a television receiver which is used for both UHF and VHF reception.
Another object of the present invention is to provide a single antenna system for UHF and VHF reception without utilization of added crossover or switching networks.
A further object of the present invention is to provide a single indoor antenna system for VHF and UHF television reception which allows separate UHF and VHF antennas to be selectively connected to the television receiver.
The single UHF/VHF antenna system of the present invention utilizes the intrinsic impedance of the input coupling network of each tuner by serially interconnecting the two tuners. Short internal leads from the terminal block to the two tuners, and especially the leads to the VHF tuner which ideally should be less than one-quarter wave length at the highest UHF frequency to be received, enables the tuner input coupling network impedances to act as the only crossover network. By combining internal and external connections in conjunction with a terminal board, each tuner is made accessible to being coupled to an individual antenna.